This article explores the press and the publications of the leaders of the argentine Socialist Party in an effort to account for one of the principal lines of its ideological message: the one represented by the different uses of the term "totalitarianism". It reconstructs the way in which the "anti-totalitarian" discourse allowed the party leadership not only to condemn the regime originated in the revolution which took place in 1943 and the Peronist government which emerged from it by associating both directly with contemporary European experiences, but also to challenge the Communists and left-wing members of the Socialist Party, because of their proximity to Peronism. This ideological itinerary was all but exhausted by the beginning of the '50s, when socialist intellectuals produced their densest characterizations of Peronism as a "totalitarian" phenomenon and just before the"anti-totalitarian" agenda began to be challenged, by grass-roots socialist militants, and particularly by the youth sector of the party.